1. Field of the Invention
This invention relates to reset pulse generating devices, and more particularly to a device for producing a reset pulse by which the output of a digital system is returned to an initial state.
2. Description of the Prior Art
In the past, control of a digital system has been accomplished by clock pulses from either a built-in, or an external clock pulse oscillation circuit. Therefore, it generally follows that when, for some cause, for example, when a drop in the battery voltage for the oscillation circuit stops the production of the clock pulses, the interior condition of the digital system is latched, and its output terminal continues holding the state that existed just before the termination of oscillation.
This raises a serious problem, for example, when the same battery used as the electrical power source of the digital system also serves as an electrical power source to drive a large current load.
Suppose, for example, an apparatus such as a camera equipped with the motor driven winder is controlled by the logic of the digital system. Then, when some trouble occurs during the period of energization of the motor of the winder, or when the battery voltage necessarily drops enough to stop rotation of the motor, and, therefore, falls below a satisfactory operating level for the oscillation circuit, the clock pulses are no longer produced, and the logic for interrupting the current supply to the motor, for example, the logic for the timer no longer operates. Since, in this case, the logic causes current supply to the motor run on, the motor continues to be supplied with current. This gives rise to a big problem in that the battery generates heat and in extreme cases leaks chemicals. Such problem may be encountered in any other apparatus where the battery is used as the electrical power source of the digital system. Some solution to this has, therefore, been sought.